FK 409 ameliorates small-for-size liver graft injury by attenuation of portal hypertension and down-regulation of Egr-1 pathway

Critical Role of LSEC in Post-Hepatectomy Liver Regeneration and Failure

Liver sinusoids are lined by liver sinusoidal endothelial cells (LSEC), which represent approximately 15 to 20% of the liver cells, but only 3% of the total liver volume. LSEC have unique functions, such as fluid filtration, blood vessel tone modulation, blood clotting, inflammatory cell recruitment, and metabolite and hormone trafficking. Different subtypes of liver endothelial cells are also known to control liver zonation and hepatocyte function. Here, we have reviewed the origin of LSEC, the different subtypes identified in the liver, as well as their renewal during homeostasis. The liver has the exceptional ability to regenerate from small remnants. The past decades have seen increasing awareness in the role of non-parenchymal cells in liver regeneration despite not being the most represented population. While a lot of knowledge has emerged, clarification is needed regarding the role of LSEC in sensing shear stress and on their participation in the inductive phase of regeneration by priming the hepatocytes and delivering mitogenic factors. It is also unclear if bone marrow-derived LSEC participate in the proliferative phase of liver regeneration. Similarly, data are scarce as to LSEC having a role in the termination phase of the regeneration process. Here, we review what is known about the interaction between LSEC and other liver cells during the different phases of liver regeneration. We next explain extended hepatectomy and small liver transplantation, which lead to "small for size syndrome" (SFSS), a lethal liver failure. SFSS is linked to endothelial denudation, necrosis, and lobular disturbance. Using the knowledge learned from partial hepatectomy studies on LSEC, we expose several techniques that are, or could be, used to avoid the "small for size syndrome" after extended hepatectomy or small liver transplantation.

Liraglutide Regulates the Kidney and Liver in Diabetic Nephropathy Rats through the miR-34a/SIRT1 Pathway

PURPOSE

To explore the regulatory effects of liraglutide on the kidney and liver through the miR-34a/SIRT1 pathway with related factors in diabetic nephropathy (DN) rats.

METHODS

DN rats were randomly divided into two groups (n = 10) and were injected with liraglutide or normal saline twice a day. The 24-hour urine microalbumin content and biochemical index levels were measured. qRT-PCR was performed to detect the expression of miR-34a in the kidney and liver tissues. The levels of SIRT1, HIF-1a, Egr-1, and TGF-β1 in kidney and liver tissues were determined using qRT-PCR, western blot, and immunohistochemistry. Electron microscopy and HE staining were used to observe the ultrastructure and pathological changes.

RESULTS

Liraglutide treatment in DN rats decreased blood glucose, 24-hour urine microalbumin, TC, TG, LDL-C, UA, Cr, UREA, ALT, and AST levels and increased the level of HDL-C (P < 0.05). Compared with the control group, the miR-34a levels were significantly decreased in kidney and liver tissues followed by liraglutide treatment (P < 0.05). The levels of SIRT1 in the liraglutide group are significantly higher than those in the control group with the kidney and liver tissues (P < 0.05). Conversely, the contents of HIF-1a, Egr-1, and TGF-β1 were significantly lower in the liraglutide group than in the control group (P < 0.05). Electron microscopy showed that the kidney of the liraglutide-treated group exhibited minor broadening of the mesangial areas, fewer deposits, and a well-organized foot process. HE staining revealed that the kidney of the liraglutide-treated rats had a more regular morphology of the glomerulus and Bowman sac cavity and lighter tubular edema. Additionally, the liraglutide-treated DN rats had a clear hepatic structure, a lower degree of steatosis, and mild inflammatory cell infiltration.

CONCLUSION

Liraglutide, through its effect on the miR-34a/SIRT1 pathway, may have a protective role in the kidney and liver of DN rats.

A Novel Method for the Prevention and Treatment of Small-for-Size Syndrome in Liver Transplantation

BACKGROUND

Currently there is no consensus on the optimal management of small-for-size syndrome following liver transplantation. Here we describe a technique to alleviate portal hypertension and improve the hepatocyte reperfusion in small-for-size liver transplantation in a Lewis rat model.

METHODS

The rats underwent trans-portal vein intra-hepatic portosystemic shunt using a self-developed porous conical tube (TPIPSS: Fig. 1) on small-for-size liver transplants (SFS) with right lobe graft. The treatment effect was evaluated by comparing hemodynamic parameters, morphological changes, serum parameters, ET-1 and eNOS expression, hepatocyte proliferation and apoptosis, CYP3A2 levels, postoperative complications, and survival between the two groups with SFS liver transplants.

RESULTS

Porous conical prosthesis prolonged the filling time of small-for-size grafts. Moreover, grafts with TPIPSS showed a lower portal vein pressure, improved microcirculatory flow, alleviated histological changes, decreased ET-1 and increased eNOS expressions, and significantly less damage to liver function comparing to grafts without TPIPSS. Mean survival and overall 30-day survival were significantly higher in the TPIPSS group.

CONCLUSIONS

These results demonstrate that porous conical tube as trans-portal vein intra-hepatic portosystemic shunt device is an effective way to alleviate portal vein hypertension and improve hepatocyte reperfusion after small-for-size liver transplantation.

Glutathione Peroxidase 3 Delivered by hiPSC-MSCs Ameliorated Hepatic IR Injury via Inhibition of Hepatic Senescence

Background and Aims: Down-regulation of GPx3 accelerated hepatic senescence, which further caused overwhelming inflammation and severe liver graft injury. MSCs derived from human induced pluripotent stem cells (hiPSC-MSCs) have been developed as more efficient delivery vehicle with the property of injury tropism. Here, we aimed to explore the suppressive role of GPx3 in hepatic IR injury using novel delivery system of hiPSC-MSCs.

Methods: The mice IR injury model with partial hepatectomy was established. The engineered hiPSC-MSCs delivering GPx3 was constructed. All the mice were segregated into three groups. hiPSC-MSC-GPx3, hiPSC-MSC-pCDH (vector control) or PBS were injected via portal vein after reperfusion. Liver injury was evaluated by histological and serological test. Hepatic apoptosis was detected by Tunel staining and remnant liver regeneration was assessed by Ki67 staining. The role of hepatic senescence in liver graft injury was evaluated in rat orthotopic liver transplantation model. The suppressive effect of GPx3 on hepatic senescence was examined in mice IR injury model and confirmed in vitro. Hepatic senescence was detected by SA-β-Gal and P^16/ink4a staining.

Results: GPx3 can be successfully delivered by hiPSC-MSCs into liver tissues. Histological examination showed that hiPSC-MSC-GPx3 treatment significantly ameliorated hepatic IR injury post-operation. Significantly lower LDH (891.43±98.45 mU/mL, P<0.05) and AST (305.77±36.22 IU/L, P<0.01) were observed in hiPSC-MSC-GPx3 group compared with control groups. Less apoptotic hepatocytes were observed and the remnant liver regeneration was more active in hiPSC-MSC-GPx3 group. In rat orthotopic liver transplantation model, more senescent hepatocytes were observed in small-for-size liver graft, in which GPx3 expression was significantly compromised. In mice IR injury model, hiPSC-MSC-GPx3 significantly suppressed hepatic senescence. In addition, rGPx3 inhibited cellular senescence of liver cells in a dose dependent manner. Four candidate genes (CD44, Nox4, IFNG, SERPERINB2) were identified to be responsible for suppressive effect of GPx3 on hepatic senescence.

Conclusion: Engineered hiPSC-MSCs delivering GPx3 ameliorated hepatic IR injury via inhibition of hepatic senescence.

Small-for-Size Syndrome: Bridging the Gap Between Liver Transplantation and Graft Recovery

In living donor liver transplantation, optimal graft size is estimated from values like graft volume/standard liver volume and graft/recipient body weight ratio but the final functional hepatic mass is influenced by other donor and recipient factors. Grafts with insufficient functional hepatic mass can produce a life-threatening condition with rapidly progressive liver failure called small-for-size syndrome (SFSS). Diagnosis of SFSS requires careful surveillance for signs of inadequate hepatocellular function, residual portal hypertension, and systemic inflammation that suggest rapidly progressive liver failure. Early diagnosis, symptom control, and addressing the cause of SFSS may prevent the need for retransplantation. With increased attention to avoiding donor risk, intensivists will be confronted with more SFSS recipients. In this review, we aim to outline a systematic approach to the medical management of patients with SFSS by providing a concise synopsis of general supportive care—neurological, cardiovascular, and renal support, mechanical ventilation, nutritional support, infection control, and tailored immunosuppression—with an aim to avoid end-organ damage or death and a review of current interventions including liver support devices, portal flow modulating drugs, and other experimental interventions that aim to preserve existing hepatic mass and improve conditions for hepatic regeneration. We examine evidence for SFSS interventions to provide the reader with information that may assist in clinical decision making. Points of controversy in care are purposefully highlighted to identify areas where additional experimental work is still needed. A full understanding of the pathophysiology of SFSS and measures to support liver regeneration will guide effective management.

Small-for-size syndrome in live donor liver transplantation-Pathways of injury and therapeutic strategies

Due to the severe organ shortage and the increasing gap between the supply and demand for donor grafts, live donor liver transplantation (LDLT) has become an accepted and alternative technique for the expansion of the donor pool. However, donor safety and good recipient outcomes must be balanced regarding risk stratification and decision-making within this patient population. Small-for-size syndrome (SFSS) is one of the complications encountered after LDLT, thus increasing the burden of optimizing donor graft selection and effective treatments during its occurrence. A graft-to-recipient weight ratio (GRWR) <0.8 predisposes the graft to SFSS. However, other factors may induce this complication even without a graft-to-patient size mismatch. Several strategies to prevent this complication include portal vein flow and liver outflow modulation, as well as pharmacological treatment. Also, as an entity with a multifactorial etiology, outcomes vary between right-lobe, left-lobe, and posterior-lobe donation among series encountered in the literature. In this review, we analyze the pathophysiology and classification of this complication, the state-of-the-art on management of SFSS, and the outcomes regarding the best treatment strategy on this patient population.

Impact of splenic artery ligation after major hepatectomy on liver function, regeneration and viability

It was reported that prevention of acute portal overpressure in small-for-size livers by inflow modulation results in a better postoperative outcome. The aim is to investigate the impact of portal blood flow reduction by splenic artery ligation after major hepatectomy in a murine model. Forty-eight rats were subjected to an 85% hepatectomy or 85% hepatectomy and splenic artery ligation. Both groups were evaluated at 24, 48, 72 and 120 post-operative hours: liver function, regeneration and viability. All methods and experiments were carried out in accordance with Coimbra University guidelines. Splenic artery ligation produces viability increase after 24 h, induces a relative decrease in oxidative stress during the first 48 hours, allows antioxidant capacity increment after 24 h, which is reflected in a decrease of half-time normalized liver curve at 48 h and at 72 h and in an increase of mitotic index between 48 h and 72 h. Splenic artery ligation combined with 85% hepatectomy in a murine model, allows portal inflow modulation, promoting an increase in hepatocellular viability and regeneration, without impairing the function, probably by inducing a less marked elevation of oxidative stress at first 48 hours.

Small for Size and Flow (SFSF) syndrome: An alternative description for posthepatectomy liver failure

Small for Size Syndrome (SFSS) syndrome is a recognizable clinical syndrome occurring in the presence of a reduced mass of liver, which is insufficient to maintain normal liver function. A definition has yet to be fully clarified, but it is a common clinical syndrome following partial liver transplantation and extended hepatectomy, which is characterized by postoperative liver dysfunction with prolonged cholestasis and coagulopathy, portal hypertension, and ascites. So far, this syndrome has been discussed with focus on the remnant size of the liver after partial liver transplantation or extended hepatectomy. However, the current viewpoints believe that the excessive flow of portal vein for the volume of the liver parenchyma leads to over-pressure, sinusoidal endothelial damages and haemorrhage. The new hypothesis declares that in both extended hepatectomy and partial liver transplantation, progression of Small for Size Syndrome is not determined only by the "size" of the liver graft or remnant, but by the hemodynamic parameters of the hepatic circulation, especially portal vein flow. Therefore, we suggest the term "Small for Size and Flow (SFSF)" for this syndrome. We believe that it is important for liver surgeons to know the pathogenesis and manifestation of this syndrome to react early enough preventing non-reversible tissue damages.

Serum levels of endothelin-1 after liver resection as an early predictor of postoperative liver failure. A prospective study

AIM

Besides the residual liver volume, damage of the microcirculation secondary to increased portal blood flow is a main determinant of postoperative liver failure (PLF). Endothelin-1 (ET-1), produced by sinusoidal endothelial cells, plays a key role in the regulation of hepatic microcirculation. The aim of this study was to determine whether ET-1 levels has any prognostic utility in predicting PLF.

METHODS

Patients undergoing liver resection for primary or secondary liver tumors at San Raffaele Hospital, Milan, were prospectively enrolled in the study. Serial postoperative serum ET-1 levels in patients undergoing liver resections were correlated with indices of inflammatory response, liver failure and death.

RESULTS

A total of 144 patients were included. ET-1 levels in patients who underwent major or extended liver resection were significantly higher than in patients who had a minor resection on postoperative day (POD) 1 (P = 0.003), POD 2 (P = 0.0001) and POD 5 (P = 0.0001). Eight patients developed PLF and ET-1 was significantly higher compared with patients without PLF on POD 2 (P = 0.002) and POD5 (P = 0.006). Serum ET-1 concentration on POD 2 was an independent predictor of PLF in multivariate analysis.

CONCLUSION

ET-1 is as an early index of PLF and provides a rationale for therapeutic manipulation, with many potential clinical implications to prevent PLF onset and reduce its severity.

The microRNA-146a/b attenuates acute small-for-size liver graft injury in rats

BACKGROUND & AIMS

A critical role of the Toll-like receptor (TLR)-4 and its downstream mediators in the pathogenesis of small-for-size liver graft injury has been documented. Recently, the microRNA-146 (miR-146) was identified as a potent negative regulator of the TLR4 signalling pathway. In this study, the role of miR-146a and miR-146b in the attenuation of TLR-4 signalling and small-for-size liver graft injury was investigated.

METHODS

The expression levels of miR-146a and miR-146b during small-for-size liver graft injury were studied in vivo. In addition, the effects of miR-146a and miR-146b on the expression of IRAK1 and TRAF6 in the rat macrophage cell line NR8383 and rat liver kupffer cells were studied in vitro. The in vivo effect of miR-146a and miR-146b on small-for-size liver graft injury was studied by the tail vein injection of miR-146a mimics and miR-146b mimics.

RESULTS

The levels of miR-146a and miR-146b decreased with a small-for-size liver graft. MiR-146a and miR-146b inhibited IRAK1 and TRAF6 expression by binding to the 3'UTR of IRAK1 or TRAF6, respectively, in the rat macrophage cell line NR8383. The administration of miR-146a mimics and miR-146b mimics prevented liver graft injury in small-for-size liver graft injury via the inactivation of IRAK1 and TRAF6 in vivo.

CONCLUSIONS

miR-146a and miR-146b prevent liver injury in small-for-size liver graft injury via the inactivation of IRAK1 and TRAF6.

Hepatoprotective effect by pretreatment with olprinone in a swine partial hepatectomy model

Excessive portal flow to a small remnant liver or small-for-size graft is a primary factor of small-for-size syndrome. We demonstrated that olprinone (OLP), a phosphodiesterase III inhibitor, had a hepatoprotective effect in a rat extended hepatectomy model and a small-for-size liver transplantation model through a modification of the portal venous pressure (PVP). To identify the appropriate dose and duration of treatment for clinical applications, we conducted experiments with a swine partial hepatectomy model. Twenty microminipigs were divided into 4 groups that received the following treatments: (A) saline (control group), (B) OLP at 0.3 μg/kg/minute (preoperative and postoperative administration), (C) OLP at 0.1 μg/kg/minute (preoperative administration), and (D) OLP at 0.3 μg/kg/minute (preoperative administration). The pigs underwent 70% partial hepatectomy. Hemodynamic changes, including changes in PVP, were examined. Liver biopsy was performed 1 and 3 hours after hepatectomy. Blood samples were collected until postoperative day 7 (POD7). In comparison with group A, PVP elevations, periportal edema, and sinusoidal hemorrhaging were attenuated after left Glisson's ligation in groups C and D. Pretreatment with OLP in groups C and D preserved the microstructure of sinusoids and improved the prothrombin activity 1 and 3 hours after hepatectomy. These animals showed better recovery of the remnant liver volume and the plasma disappearance rate of indocyanine green on POD7. In contrast, group B showed exacerbation of liver damage. Measurements of the serum OLP concentration showed that 10 ng/mL OLP was appropriate for a hepatoprotective effect. In conclusion, pretreatment with OLP shows hepatoprotective effects in a swine partial hepatectomy model. OLP may have the potential to ameliorate patients' outcomes after hepatectomy or liver transplantation.

Small-for-size syndrome in living-donor liver transplantation using a left lobe graft

In living-donor liver transplantation with a left lobe graft, which can reduce the burden on the donor compared to right lobe graft, the main problem is small-for-size (SFS) syndrome. SFS syndrome is a multifactorial disease that includes aspects related to the graft size, graft quality, recipient factors and even technical issues. The main pathophysiology of SFS syndrome is the sinusoidal microcirculatory disturbance induced by shear stress, which is caused by excessive portal inflow into the smaller graft. The donor age, the presence of steatosis of the graft and a poor recipient status are all risk factors for SFS syndrome. To resolve SFS syndrome, portal inflow modulation, splenectomy, splenic artery modulation and outflow modulation have been developed. It is important to establish strict criteria for managing SFS syndrome. Using pharmacological interventions and/or therapeutic approaches that promote liver regeneration could increase the adequate outcomes in SFS liver transplantation. Left lobe liver transplantation could be adopted in Western countries to help resolve the organ shortage.

Losartan supports liver regrowth via distinct boost of portal vein pressure in rodents with 90 % portal branch ligation

OBJECTIVES

The study used a model of 90 % portal branch ligation (PBL) in rats to study the effect of losartan on portal vein pressure (PVP) and liver regeneration in rats after PBL.

METHODS

A total of 144 male Sprague-Dawley rats were arbitrarily designated into three treatment method groups: a sham operation group (Sham), a PBL treatment group (PBL), and a PBL plus losartan treatment group (PBL + L). Losartan (2 mg/day) was intragastrically gavaged 3 days before the PBL or sham operation to time points of study.

RESULTS

Both the PBL and PBL + L groups showed an intense surge in PVP after PBL treatment, peaking at 12 h postsurgery, then lessening progressively afterwards. PVP was substantially greater in these two groups compared with the Sham group at 6-72 h postsurgery (p < 0.01). Compared with the PBL group, the PBL + L group showed a noticeable reduction in PVP 6-48 h postsurgery (p < 0.05); the PBL group showed considerably raised levels of plasma ALT and AST 6-72 h postsurgery (p < 0.01). Compared to the PBL group, the PBL + L group showed drastically reduced plasma ALT and AST levels 12-72 h postsurgery (p < 0.05).

CONCLUSIONS

Losartan supports liver regeneration in 90 % of rats that underwent PBL. The mechanism may be related to losartan's ability to regulate PVP and increase serum hepatocyte growth factor levels.

Suppression of liver regeneration affects hepatic graft survival in small-for-size liver transplantation in rats

AIM

  Small-for-size liver transplantation (SFSLT) often results in hepatic graft failure and decreased survival. The present study was aimed to investigate the possible mechanism of hepatic graft failure in SFSLT in rats.

METHODS

  Rat models of full-size orthotopic liver transplantation, 50% partial liver transplantation and 30% partial liver transplantation were established. Proliferative responses of the hepatic graft were evaluated by immunohistochemical staining and western blotting. Apoptosis-, inflammatory-, anti-inflammatory- and growth factor-related genes were screened by quantitative reverse transcription polymerase chain reaction. Activities of transcription factors of AP-1 and nuclear factor (NF)-κB were analyzed by electrophoretic mobility shift assay.

RESULTS

  A 30% partial liver transplant not only resulted in marked structural damages to the hepatic graft, but also showed the lowest 7-day survival rate. In addition, sup pressed expressions of proliferating cell nuclear antigen (PCNA) and cyclin D1 by immunohistochemical staining and decreased expressions of cyclin D1 and p-c-Jun by western blotting were detected. Downregulated expressions of Bcl-2, Bcl-XL, interleukin (IL)-6, IL-10, IP-10 and CXCR2, upregulated expression of tumor necrosis factor-α, and decreased levels of AP-1 and NF-κB were also found following 30% partial liver transplantation after reperfusion.

CONCLUSION

  Liver regeneration is remarkably suppressed in SFSLT. The significant changes of intra-graft gene expression described above indicated that ischemia reperfusion injury would be severe in 30% partial liver transplantation. The capability of liver regeneration secondary to ischemia reperfusion injury might determine hepatic graft survival in SFSLT.

Effect of olprinone on liver microstructure in rat partial liver transplantation

BACKGROUND

Donor safety is a major concern in living-donor liver transplantation. However, partial grafts do not meet the functional demands of recipients and lead to small-for-size syndrome (SFSS). In a previous study, we showed that olprinone (OLP), a selective phosphodiesterase ІІІ inhibitor, up-regulates endothelial nitric oxide synthase level in the liver and attenuates shear stress, sinusoidal endothelial cell injury, and hepatocyte apoptosis after excessive liver resection in a rat model. We aimed to examine whether OLP treatment has beneficial effects on SFSS in a rat model of partial liver transplantation (PLT).

METHODS

We performed experiments in a rat model of 30% PLT. In the OLP group, we inserted an osmotic pump with OLP into the peritoneal cavity 48 h before liver graft sampling. Recipient rats were not treated with OLP. We examined the liver microstructure by electron microscopy and biochemical examination, and determined the 7-d survival of recipients.

RESULTS

In the OLP group 1 h after PLT, the sinusoidal endothelial cells of the liver were well preserved and we observed few vacuolar structures in hepatocytes. The total serum bilirubin level 1 wk after PLT tended to be lower in the OLP group than in the controls, and the liver microstructures were also well preserved in the OLP group. The probability of survival in the OLP group (100%; 14 of 14 rats) was significantly higher than that in the control group (75%; 15 of 20 rats).

CONCLUSIONS

Olprinone treatment was demonstrated to have therapeutic potential to overcome SFSS.

Dual cytoprotective effects of splenectomy for small-for-size liver transplantation in rats

The problems associated with small-for-size liver grafts (ie, high mortality rates, postoperative complications, and acute rejection) remain critical issues in partial orthotopic liver transplantation (OLT). In association with partial OLT, splenectomy (SP) is a procedure used to reduce the portal pressure. However, the precise effects of SP on partial OLT have been unclear. In this study, using small-for-size liver grafts in rats, we examined the cytoprotective effects of SP on OLT. Liver grafts were assigned to 2 groups: a control group (OLT alone) and an SP group (OLT after SP). SP significantly increased animal survival and decreased liver damage. SP exerted the following cytoprotective effects: (1) it improved hepatic microcirculation and prevented increases in the portal pressure after OLT, (2) it suppressed the hepatic infiltration of neutrophils and macrophages through the direct elimination of splenic inflammatory cells before OLT, (3) it decreased the hepatic expression of tumor necrosis factor α and interleukin-6, (4) it attenuated sinusoidal endothelial injury, (5) it decreased plasma endothelin 1 levels and increased hepatic heme oxygenase 1 expression, (6) it suppressed hepatocellular apoptosis through the down-regulation of hepatic caspase-3 and caspase-8 activity, and (7) it increased hepatic regeneration. In conclusion, SP for small-for-size grafts exerts dual cytoprotective effects by preventing excessive portal vein hepatic inflow and eliminating splenic inflammatory cell recruitment into the liver; this in turn inhibits hepatocellular apoptosis and improves liver regeneration.

The nitric oxide pathway--evidence and mechanisms for protection against liver ischaemia reperfusion injury

Ischaemia reperfusion (IR) injury is a clinical entity with a major contribution to the morbidity and mortality of liver surgery and transplantation. A central pathway of protection against IR injury utilizes nitric oxide (NO). Nitric oxide synthase (NOS) enzymes manufacture NO from L-arginine. NO generated by the endothelial NOS (eNOS) isoform protects against liver IR injury, whereas inducible NOS (iNOS)-derived NO may have either a protective or a deleterious effect during the early phase of IR injury, depending on the length of ischaemia, length of reperfusion and experimental model. In late phase hepatic IR injury, iNOS-derived NO plays a protective role. In addition to NOS consumption of L-arginine during NO synthesis, this amino acid may also be metabolized by arginase, an enzyme whose release is increased during prolonged ischaemia, and therefore diverts L-arginine away from NOS metabolism leading to a drop in the rate of NO synthesis. NO most commonly acts through the soluble guanylyl cyclase-cyclic GMP- protein kinase G pathway to ameliorate hepatic IR injury. Both endogenously generated and exogenously administered NO donors protect against liver IR injury. The beneficial effects of NO on liver IR are not, however, universal, and certain conditions, such as steatosis, may influence the protective effects of NO. In this review, the evidence for, and mechanisms of these protective actions of NO are discussed, and areas in need of further research are highlighted.

Implanted adipose-derived stem cells attenuate small-for-size liver graft injury by secretion of VEGF in rats

Graft injury after small-for-size liver transplantation impairs graft function and threatens the survival of the recipients. The use of adipose-derived stem cells (ADSCs) for liver injury protection and repair is promising. Our aim was to investigate the role of vascular endothelial growth factor (VEGF) secreted by ADSCs in the treatment of small-for-size liver graft injury. Studies were performed using ADSCs with VEGF secretion blocked by RNA interference. In vitro, ADSCs prevented apoptosis of freshly isolated liver sinusoidal endothelial cells (LSECs) by secretion of VEGF. Syngeneic 35% orthotopic liver transplantation followed by implantation of syngeneic ADSCs through the portal vein system was performed using Wistar rats. We found VEGF secreted by implanted ADSCs improved graft microcirculatory disturbances, serum liver function parameters and survival. The improved microcirculatory status was also reflected by reduced hepatocellular damage, especially LSEC apoptosis and improved liver regeneration. These effects were accompanied by decreased expression of endothelin receptor type A, increased Bcl-2/Bax ratio, decreased expression of Bad and elevated proportion of phosphorylated Bad. In conclusion, implanted syngeneic ADSCs attenuated small-for-size liver graft injuries and subsequently enhanced liver regeneration in a rat 35% liver transplantation model. The VEGF secreted by implanted ADSCs played a crucial role in this process.

Acute milk yield response to frequent milking during early lactation is mediated by genes transiently regulated by milk removal

Milking dairy cows four times daily (4×) instead of twice daily (2×) during early lactation stimulates an increase in milk yield that partly persists through late lactation; however, the mechanisms behind this response are unknown. We hypothesized that the acute mammary response to regular milkings would be transient and would involve different genes from those that may be specifically regulated in response to 4×. Nine multiparous cows were assigned at parturition to unilateral frequent milking (UFM; 2× of the left udder half, 4× of the right udder half). Mammary biopsies were obtained from both rear quarters at 5 days in milk (DIM), immediately after 4× glands had been milked (experiment 1, n = 4 cows), or 2.5 h after both udder halves had last been milked (experiment 2, n = 5 cows). Affymetrix GeneChip Bovine Genome Arrays were used to measure gene expression. We found 855 genes were differentially expressed in mammary tissue between 2× vs. 4× glands of cows in experiment 1 (false discovery rate ≤ 0.05), whereas none were differentially expressed in experiment 2 using the same criterion. We conclude that there is an acute transcriptional response to milk removal, but 4× milking did not elicit differential expression of unique genes. Therefore, there does not appear to be a sustained transcriptional response to 4× milking on day 5 of lactation. Using a differential expression plot of data from both experiments, as well as qRT-PCR, we identified at least two genes (chitinase 3-like-1 and low-density lipoprotein-related protein-2 that may be responsive to both milk removal and to 4× milking. Therefore, the milk yield response to 4× milking may be mediated by genes that are acutely regulated by removal of milk from the mammary gland.

A better way to do small-for-size liver transplantation in rats

Establishing a model for small-for-size liver transplantation is the basis for this study of partial and living donor graft liver transplantation. This study aims to explore a simpler and more effective way of establishing a 30% small-for-size liver transplantation in rats. Sprague-Dawley rats were selected as the donors and recipients. Small-for-size orthotopic liver transplantation was performed using Kamada's two-cuff method. The donor's liver was flushed via the abdominal aorta and hepatectomy was performed in situ. The animals were divided into three groups depending on the graft selected, with 40 pairs of rats in each group. In group I, the median lobe of the liver was used as graft; in group II, the right half of the median lobe and the right lobe were used as graft; and in group III, the median and right lobes were used as graft. In groups I and II, the bodyweights of donors were the same as those of recipients; however, in group III the bodyweights of donors were 100-120 g less than those of the recipients. The duration needed for transplantation, the 7-day survival rates, and the technical complication rates were compared among these three groups. The time required for hepatectomy was shorter in group III compared with groups I and II (8.8±0.7 min vs. 11.5±1.1 min and 10.1±1.0 min, P = 0.001). The cold ischemia time for the grafts, the anhepatic times, and the transplantation times for the recipients were not significantly different among the three groups. Compared with groups I and II, the incidence of bleeding, bile leakage, and inferior vena caval strictures were significantly decreased in group III (P<0.05). No significant differences between the three groups were found based on other complications after the operation (P>0.05). Group III had better 7-day survival rates and longer median survival times but the differences were not statistically significant. The method of small for donor bodyweight using the median and right lobes for grafting may be a more effective and simpler way of establishing a 30% small-for-size liver transplantation in rats, as shown by the shorter hepatectomy time and the occurrence of fewer complications after the operation.

Inhibition of inducible nitric oxide synthase worsens liver damage regardless of lipopolysaccharide treatment in small-for-size liver transplantation

OBJECTIVE

In small-for-size liver transplantation, portal hypertension aggravates endotoxin from the gut which accelerates the activation of inducible nitric oxide synthase (iNOS). However, there is little knowledge as to the effects of iNOS inhibitors on small-for-size graft damage. Our study was designed to investigate the role of an iNOS inhibitor both with and without lipopolysaccharide (LPS) treatment in ischemia-reperfusion injury of small-for-size liver transplantation.

METHODS

Subjecting Sprague-Dawley rats to small-for-size grafts liver transplantation, we investigated the time course of changes in hepatic expression of iNOS and endothelial nitric oxide synthase (eNOS). Meantime, we also investigated the effects of iNOS inhibitor, both with and without LPS treatment, at 6h after reperfusion.

RESULTS

While iNOS mRNA expression reached a peak at 3h, the highest protein level occurred at 6h after reperfusion. Aminoguanidine (AG) significantly inhibited mRNA and protein expressions of iNOS, but not that of eNOS. However, LPS accelerated activation of iNOS, but suppressed the expression of eNOS. Meanwhile, compared with the untreated group, those treated with AG or LPS experienced worsened liver function and tissue damage, promoting neutrophil infiltration in the liver tissue. The difference between the LPS group and the LPS+AG group was found to be significant. In addition, AG and LPS treatments up-regulated the protein expression of ICAM-1 and NF-kappaB p65.

CONCLUSION

In a small-for-size model of rat liver transplantation, regardless of LPS treatment, the inhibitor of iNOS, AG, attenuated iNOS expression, but worsened liver function and tissue damage. The subsequent increased neutrophil infiltration in liver tissue may be associated with up-regulation of ICAM-1 and NF-kappaB expressions.

Portal hyperperfusion: mechanism of injury and stimulus for regeneration in porcine small-for-size transplantation

Understanding the pathogenesis of small-for-size (SFS) syndrome is critical to expanding the applicability of partial liver transplantation. We aimed to characterize its acute presentation and association with alterations in hepatic hemodynamics, microstructure, and regeneration in a porcine model. Eighteen SFS liver transplants were performed. Donors underwent 70% hepatectomy. Partial grafts were implanted into larger recipients. Whole liver transplants were also performed (n = 6). Recipients were followed until death or for 5 days. Hemodynamics were measured, and tissue was sampled intraoperatively and at the study end. Serum was sampled regularly during follow-up. Seventeen SFS transplants and 6 whole liver transplants were included. SFS grafts represented 23.2% (19.3%-25.3%) of the recipients' standard liver volume. The survival rate was 29% and 100% in the SFS and whole liver groups, respectively. The portal venous flow, pressure gradient, and resistance were significantly higher in recipients of SFS grafts versus whole livers after portal and arterial reperfusion. Arterial flow as a percentage of the total liver blood flow was significantly lower after reperfusion in SFS grafts and remained so when measured again after 5 days. Markers of endothelial cell injury increased soon after reperfusion, and those of hepatocellular injury increased later; both predicted the appearance of either graft failure or histological recovery. Proliferative activity peaked earlier and higher among nonsurvivors in the SFS group. Surviving grafts demonstrated a slower but maintained rise in regenerative activity, although metabolic activity failed to improve. In SFS transplantation in the acute setting, portal hyperperfusion is a stimulus for regeneration but may simultaneously cause irreparable endothelial injury. This porcine model not only helps to elucidate the inciting factors in SFS pathogenesis but also offers a clinically relevant means to study its prevention.

Sinusoidal microcirculatory changes after small-for-size liver transplantation in rats

Small-for-size graft injury is characterized by portal venous hypertension and loss of intracellular homeostasis early after transplant. The long-term alteration of sinusoidal microcirculatory hemodynamic state remains unknown. A syngeneic rat orthotopic liver transplantation model was developed using small-for-size grafts (35% of recipient liver weight) or whole grafts (100% of recipient liver weight). Graft survival, portal pressure, liver function, hepatocellular apoptosis as well as morphological changes (by light microscopy and electron microscopy) were assessed. Sinusoidal microcirculatory hemodynamics was examined by intravital fluorescence microscopy. Although portal hypertension lasted only for 1 h after performance of small-for-size liver transplantation, a sustained microcirculatory disturbance was accompanied by dramatic reduction of sinusoidal perfusion rate, elevation of sinusoidal diameter as well as increase in the number of apoptotic hepatocytes during the first 7 days. These resulted in lower survival rate (50% vs. 100%, P = 0.012), higher level of liver function, and more severe morphological changes, which could induce small-for-size syndrome. In conclusion, persistent microcirculatory hemodynamic derangement during the first 7 days after reperfusion as well as transient portal hypertension is significant manifestation after small-for-size liver transplantation. Long-term microcirculation disturbance displayed as decrease of sinusoidal reperfusion area and increase of spread in functional liver mass seems to be the key factor for graft injuries.

N-n-butyl haloperidol iodide protects cardiac microvascular endothelial cells from hypoxia/reoxygenation injury by down-regulating Egr-1 expression

AIMS

Our previous studies have shown that N-n-butyl haloperidol iodide (F2) can antagonize myocardial ischemia/reperfusion (I/R) injury by down-regulating the early growth response (Egr)-1 expression, but the molecular mechanisms are not well understood. Because there is evidence implicating myocardial I/R injury is closely associated with endothelial dysfunction. The present study is to test the hypothesis that the protective effects of F2 on myocardial I/R injury is related closely with down-regulating Egr-1 expression on cardiac microvascular endothelial cells (CMECs).

METHODS

A model of cultured CMECs exposed to hypoxia/reoxygenation (H/R) was developed. With antisense Egr-1 oligodeoxyribonucleotide (ODN), the relationship between Egr-1 expression and endothelial H/R injury was investigated. Egr-1 mRNA and protein expression were examined by real-time fluorescent quantitative PCR, immunocytochemical staining and Western-blot analysis. Lactate dehydrogenase (LDH), malondialdehyde (MDA), superoxide dismutase (SOD), intercellular adhesion molecule-1 (ICAM-1), adherence of neutrophil and platelets, and cell viability were measured after H/R to evaluate the degree of endothelial injury.

RESULTS

Pretreatment with antisense Egr-1 ODN significantly reduced Egr-1 protein expression and attenuated injury of CMECs. Consistent with down-regulation of Egr-1 expression by F2, inflammation and other damage were significantly reduced as evidenced by a decrease of ICAM-1 expression, reduction of neutrophil and platelets adherence, increase in SOD, and decreases in MDA and LDH levels, resulting in the rise of cell viability.

CONCLUSIONS

We demonstrate a protective effect of F2 in CMECs against H/R injury by down-regulating Egr-1 expression, which might be play a vital role in the pathogenesis of myocardial I/R injury.

Liver Transplantation in Asia: Past, Present and Future

With the technical advances and improvements in perioperative management and immunosuppressants, liver transplantation is the standard treatment for patients with end-stage liver diseases. In Asia, a shortage of deceased donor liver grafts is the universal problem to be faced with in all transplant centres. Many surgical innovations are then driven to counteract this problem. This review focuses on 3 issues that denote the development of liver transplantation in Asian countries. These include living donor liver transplantation (LDLT), split liver transplantation (SLT) and liver transplantation for hepatocellular carcinoma (HCC). Minimal graft weight, types of liver graft to donate and the inclusion of the middle hepatic vein with the graft are the main issues to be established in LDLT. The rapid growth and wide dissemination of LDLT has certainly alleviated the supply-and-demand problem of liver grafts in Asia. SLT is another attractive approach. Technical expertise, donor selection and graft allocation are the main determinants for its success. Liver transplantation plays a key role in the management of HCC in Asia. LDLT would be the main strategy in this aspect. The issue of extending the selection criteria for HCC patients for LDLT is still controversial. On the whole, future developments to increase the donor pool for the expanding recipient need in Asia would involve transplantation from non-heart beating donor and ABO incompatible transplantation.

The Pringle manoeuvre should be avoided in hepatectomy for cancer patients due to its side effects on tumor recurrence and worse prognosis

Curative hepatectomy is still the best therapeutic strategy for liver cancer treatment up to now. The Pringle manoeuvre has been commonly used to avoid massive blood loss during operation since its advent, which greatly accelerates the advance of liver surgery and oncological surgery. In the past century, more attentions have been paid to different effects of ischemia-reperfusion injury elicited by Pringle manoeuvre. Theses include its impacts on complex metabolic, immunological, and microvascular changes, which altogether might contribute to hepatocellular damage and dysfunction, and contribute to haemodynamic instability. Despite these adverse impacts, the short-term outcome of affected patients under hepatectomy was greatly improved with the advances of surgical techniques and perioperative management in recent years. While the long-term prognosis remains unsatisfactory due to a high incidence of intra/extrahepatic recurrence. The reason for it was not totally elucidated. Furthermore, the effect of the Pringle manoeuvre on the prognosis of oncologic patients and behavior of the tumor cell was not deliberately mentioned. This point was put forward to the front-desk by the specific phenomenon from recent animal studies. It is showed that ischemia-reperfusion injury of the liver remnant may be a significant factor to promote the tumor recurrence and metastasis. If it is a truth in human, there must be a big challenge to the Pringle manoeuvre. So we hypothesized that the long-term prognosis of cancer patients could be worsened by the ischemia-reperfusion injury elicited by Pringle manoeuvre during the hepatectomy and it should be revised, or even, avoided in future hepatectomy for oncologic patients. The less surgical stress including ischemia-reperfusion injury in the hepatic resection without Pringle manoeuvre might contribute to a better prognosis. To get a deeper understanding, prospective randomized clinical trials need to be done. It is surely supposed to provide more important information about the long-term effects of the Pringle manoeuvre, and to our hypothesis.

Historical perspective of living donor liver transplantation

Living donor liver transplantation (LDLT) has gone through its formative years and established as a legitimate treatment when a deceased donor liver graft is not timely or simply not available at all. Nevertheless, LDLT is characterized by its technical complexity and ethical controversy. These are the consequences of a single organ having to serve two subjects, the donor and the recipient, instantaneously. The transplant community has a common ground on assuring donor safety while achieving predictable recipient success. With this background, a reflection of the development of LDLT may be appropriate to direct future research and patient-care efforts on this life-saving treatment alternative.

Ischemia-reperfusion of small liver remnant promotes liver tumor growth and metastases--activation of cell invasion and migration pathways

Elucidating the mechanism of liver tumor growth and metastasis after hepatic ischemia-reperfusion (I/R) injury of a small liver remnant will lay the foundation for the development of therapeutic strategies to target small liver remnant injury, and will reduce the likelihood of tumor recurrence after major hepatectomy or liver transplantation for liver cancer patients. In the current study, we aimed to investigate the effect of hepatic I/R injury of a small liver remnant on liver tumor development and metastases, and to explore the precise molecular mechanisms. A rat liver tumor model that underwent partial hepatic I/R injury with or without major hepatectomy was investigated. Liver tumor growth and metastases were compared among the groups with different surgical stress. An orthotopic liver tumor nude mice model was used to further confirm the invasiveness of the tumor cells from the above rat liver tumor model. Significant tumor growth and intrahepatic metastasis (5 of 6 vs. 0 of 6, P=0.015), and lung metastasis (5 of 6 vs. 0 of 6, P=0.015) were found in rats undergoing I/R and major hepatectomy compared with the control group, and was accompanied by upregulation of mRNA levels for Cdc42, ROCK (Rho kinase), and vascular endothelial growth factor, as well as activation of hepatic stellate cells. Most of the nude mice implanted with liver tumor from rats under I/R injury and major hepatectomy developed intrahepatic and lung metastases. In conclusion, hepatic I/R injury of a small liver remnant exacerbated liver tumor growth and metastasis by marked activation of cell adhesion, invasion, and angiogenesis pathways.

Donor pretreatment with FK506 reduces reperfusion injury and accelerates intestinal graft recovery in rats

BACKGROUND

FK506 alleviates warm ischemia-reperfusion injury, but it remains unknown if such protection is manifest after cold storage and transplantation. We studied the early outcome after transplantation of intestines from donors pretreated with FK506 compared to grafts from controls treated with saline (154 mM NaCl).

METHODS

Sprague-Dawley rats received 0.3 mg/kg FK506 or saline intravenously 6 hours before graft retrieval. The small bowel was harvested, stored for 3 hours, and then transplanted heterotopically. Samples were taken after preservation and at 20 minutes, 6 hours, 12 hours, and 24 hours after reperfusion. Heat shock protein 72 (Hsp72) and iintercellular adhesion molecule (ICAM)-1 expression and nuclear factor kappaB (NF-kappaB) activation were assessed via Western blots and eelectrophoretic mobility shift assay (EMSA), respectively. Dissacharidase activity and enterocyte proliferation rate were also studied.

RESULTS

Preservation injury was similar between groups, but pretreated grafts had better morphology already 20 minutes after reperfusion. Control grafts always had thinner mucosa and more PMN infiltration. Hsp72 expression was greater in pretreated grafts. ICAM-1 was absent after harvesting, preservation, and immediately after reperfusion but increased in control grafts at the later time points. Control grafts showed a biphasic NF-kappaB activation pattern, whereas NF-kappaB activation was inhibited effectively in pretreated grafts. Dissacharidase activity decreased during the first 6 hours after reperfusion but recovered within 24 hours in pretreated grafts but not in control grafts. Earlier enterocyte proliferation was observed in pretreated grafts.

CONCLUSIONS

FK506 donor pretreatment reduced graft proinflammatory activation and neutrophil inflammation. Pretreated groups revealed a milder reperfusion injury and accelerated morphologic and functional recovery. The mechanisms involved appear to involve Hsp72 upregulation and NF-kappaB inhibition.

Protective effect of adenosine A2A receptor activation in small-for-size liver transplantation

The aim of the present study was to investigate the potential role of adenosine A(2A) receptor (A(2A)R) activation in small-for-size liver transplantation. A rat orthotopic liver transplantation model was performed by using 40% (range: 36-46%) liver grafts. Recipients were given either saline (control group) or CGS 21680 (2-p-(2-Carboxyethyl)phenethylamino-5'-N-ethylcarboxamidoadenosine hydrochloride, a selective A(2A)R agonist), or CGS 21680+ ZM 241385 (a selective A(2A)R antagonist) immediately after reperfusion for 3 h. Compared with control group, CGS 21680 used at both low dose (0.05 microg/kg/min) and high dose (0.5 microg/kg/min) increased the survival rate from 16.7% (2/12) to 83.3% (10/12) and 66.7% (8/12), respectively. These effects correlated with improved liver function and preserved hepatic architecture. CGS 21680 effectively decreased neutrophil infiltration, suppressed pro-inflammatory (TNF-alpha, IL-1beta and IL-6) expression, promoted expression of antiapoptotic molecules, and inhibited apoptosis. The effects of CGS 21680 were prevented when ZM 241385 was co-administrated. In conclusion, the present study showed that A(2A)R activation alleviated portal hypertension, suppressed inflammatory response, reduced apoptosis, and potentiated the survival of small-for-size liver grafts. Our findings provide the rationale for a novel therapeutic approach using A(2A)R activation to maximize the availability of small-for-size liver grafts.

The protective effects of N-n-butyl haloperidol iodide on myocardial ischemia-reperfusion injury in rats by inhibiting Egr-1 overexpression

AIMS

Our previous studies have shown that N-n-butyl haloperidol iodide (F(2)) can antagonize myocardial ischemia/reperfusion (I/R) injury by blocking intracellular Ca(2+) overload. The present study is to test the hypothesis that the protective effects of F(2) on myocardial I/R injury is mediated by downregulating Egr-1 expression.

METHODS

The Sprague-Dawley rat myocardial I/R model and cardiomyocyte hypoxia/reoxygenation (H/R) model were established. With antisense Egr-1 oligodeoxyribonucleotide (ODN), the relationship between Egr-1 expression and myocardial I/R injury was investigated. Hemodynamic parameters, myeloperoxidase (MPO), cardiac troponin I (cTnI) and tumor necrosis factor-alpha (TNF-alpha) were measured to assess the degree of injury and inflammation of myocardial tissues and cells. Egr-1 mRNA and protein expressions were examined by Northern-blot and Western-blot analyses.

RESULTS

Treatment with antisense Egr-1 ODN significantly reduced Egr-1 protein expression and attenuated injury of myocardial tissues and cells. Meanwhile, treatment with F(2) significantly inhibited the overexpression of Egr-1 mRNA and protein in myocardial tissues and cells. Consistent with downregulation of Egr-1 expression by F(2), inflammation and other damages were significantly relieved evidenced by the amelioration of hemodynamics, the reduction in myocardial MPO activity as well as the decrease in leakage of cTnI and release of TNF-alpha from cardiomyocyte.

CONCLUSIONS

These results suggested that the overexpression of Egr-1 was causative in myocardial I/R or H/R injury, and F(2) could protect myocardial tissues and cells from I/R or H/R injury, which was largely due to the inhibition of Egr-1 overexpression.

Live donor liver transplantation in adults

Live donor liver transplantation (LDLT) was initiated in 1988 for children recipients. Its application to adult recipients was limited by graft size until the first right liver LDLT was performed in Hong Kong in 1996. Since then, right liver graft has become the major graft type. Despite rapid adoption of LDLT by many centers, many controversies on donor selection, indications, techniques, and ethics exist. With the recent known 11 donor deaths around the world, transplant surgeons are even more cautious than the past in the evaluation and selection of donors. The need for routine liver biopsy in donor evaluation is arguable but more and more centers opt for a policy of liberal liver biopsy. Donation of the middle hepatic vein (MHV) in the right liver graft was considered unsafe but now data indicate that the outcome of donors with or without MHV donation is about equal. Right liver LDLT has been shown to improve the overall survival rate of patients with chronic liver disease, acute or acute-on-chronic liver failure and hepatocellular carcinoma waiting for liver transplantation. The outcome of LDLT is equivalent to deceased donor liver transplantation despite a smaller graft size and higher technical complexity.

Effects of N-n-butyl haloperidol iodide on myocardial ischemia/reperfusion injury and Egr-1 expression in rat

We have previously shown that N-n-butyl haloperidol iodide (F2) derived from haloperidol reduces ischemia/reperfusion-induced myocardial injury by blocking intracellular Ca2+ overload. This study tested the hypothesis that cardio-protection with F2 is associated with an attenuation in the expression of early growth response gene 1 (Egr-1). In an in vivo rat model of 60 min coronary occlusion followed by 180 min of reperfusion, treatment with F2 significantly reduced myocardial injury evidenced by the reduction in release of plasma creatine kinase, myocardial creatine kinase isoenzyme and lactate dehydrogenase. In cultured neonatal rat cardiomyocytes of hypoxia for 3 h and reoxygenation for 1 h, F2 treatment attenuated necrotic and apoptotic cell death, as demonstrated by electron microscopy. Concomitant with cardio-protection by F2, the increased expression levels of Egr-1 mRNA and protein were significantly reduced in myocardial tissue and cultured cardiomyocytes as detected by reverse transcription-polymerase chain reaction, immunohistochemistry and immunocytochemistry. In conclusion, these results suggest that the protective effect of F2 on ischemia/reperfusion- or hypoxia/reoxygenation-induced myocardial injury might be partly mediated by downregulating Egr-1 expression.

Rapamycin attenuates liver graft injury in cirrhotic recipient--the significance of down-regulation of Rho-ROCK-VEGF pathway

To investigate whether rapamycin could attenuate hepatic I/R injury in a cirrhotic rat liver transplantation model, we applied a rat orthotopic liver transplantation model using 100% or 50% of liver grafts and cirrhotic recipients. Rapamycin was given (0.2 mg/kg, i.v.) at 30 min before graft harvesting in the donor and 24 h before operation, 30 min before total hepatectomy and immediately after reperfusion in the recipient. Rapamycin significantly improved small-for-size graft survival from 8.3% (1/12) to 66.7% (8/12) (p = 0.027). It also increased 7-day survival rates of whole grafts (58.3%[7/12] vs. 83.3%[10/12], p = 0.371). Activation of hepatic stellate cells was mainly found in small-for-size grafts during the first 7 days after liver transplantation. Rapamycin suppressed expression of smooth muscle actin, which is a marker of hepatic stellate cell activation, especially in small-for-size grafts. Intragraft protein expression and mRNA levels of vascular endothelial growth factor (VEGF) were down-regulated by rapamycin at 48 h both in whole and small-for-size grafts. Consistently, mRNA levels and protein expression of Rho and ROCK I were decreased by rapamycin during the 48 h after liver transplantation. In conclusion, rapamycin attenuated graft injury in a cirrhotic rat liver transplantation model by suppression of hepatic stellate cell activation, related to down-regulation of Rho-ROCK-VEGF pathway.

Attenuation of acute phase shear stress by somatostatin improves small-for-size liver graft survival

The major concern of living donor liver transplantation is small-for-size graft injury at the early phase after transplantation. Novel therapeutic strategies should be developed. To investigate the protective effect of somatostatin related to hemodynamic stress on small-for-size liver graft injury, we applied a treatment regimen of low-dose somatostatin in a rat orthotopic liver transplantation model using small-for-size grafts (median, 38.7%; range, 35-42%). Somatostatin was given at 5 minutes before total hepatectomy and immediately after reperfusion in the recipient (20 microg/kg). Graft survival, portal hemodynamics, intragraft gene expression and hepatic ultrastructural changes were compared between the rats with or without somatostatin treatment. Seven-day graft survival rates in the somatostatin treatment group were significantly improved compared to the control group (66.7% vs. 16.7%, P = 0.036). In the treatment group, portal pressure and hepatic surface blood flow were significantly decreased within the first 30 minutes after reperfusion, whereas in the control group, transient portal hypertension and excessive hepatic blood flow were observed. Intragraft expression (both messenger RNA and protein) of endothelin-1 was significantly downregulated accompanied with upregulation of heme oxygenase-1 and A20. Better preservation of liver function was found in the treatment group. Hepatic ultrastructure, especially the integrity of sinusoids, was well protected in the treatment group. In conclusion, low-dose somatostatin rescues small-for-size grafts from acute phase injury in liver transplantation by attenuation of acute-phase shear stress that resulted from transient portal hypertension.

Fat-derived hormone adiponectin combined with FTY720 significantly improves small-for-size fatty liver graft survival

Owing to the discrepancy between organ donation and the demand for liver transplantation, expanding the liver donor pool is of vital importance. However, marginal liver grafts, such as small-for-size and/or fatty grafts, were associated with primary graft nonfunction or poor function. Therefore, novel combination therapies to rescue small-for-size fatty liver grafts should be investigated. In this study, we applied a combination therapy using a fat-derived hormone adiponectin (anti-steatosis) plus immunomodulator FTY720 (anti-inflammatory) in a rat liver transplantation model using small-for-size fatty liver grafts, and investigated the underlying protective mechanism such as anti-steatosis, intra-graft energy metabolism, hepatic microcirculatory changes, cell signaling cascades for survival, apoptosis and inflammation. The current study demonstrated that even a single treatment of adiponectin or FTY720 improved the 7-day graft survival from 0% to 62.5% (p = 0.001). The combination therapy significantly increased the 7-day graft survival rate to 100% by remarkable attenuation of graft steatosis and acute phase inflammatory response, significant activation of cell survival Akt pathway and maintenance of intra-graft adenosine triphosphate metabolism and improvement of hepatic microcirculation. In conclusion, the fat-derived hormone adiponectin combined with FTY720 might be a novel combination drug therapy for prevention of small-for-size fatty liver graft injury.

How ischaemic preconditioning protects small liver grafts

Interleukin-1 (IL-1) and transforming growth factor-beta (TGFbeta) are key inhibitors of hepatocyte proliferation after hepatectomy. IL-1 inhibition by heat shock proteins (HSPs) has been reported in inflammatory processes. A recent study indicated the benefits of ischaemic preconditioning in reduced-size orthotopic liver transplantation (ROLT). The present study examined: (a) the effect of ischaemic preconditioning on IL-1 and TGFbeta in ROLT; (b) whether preconditioning protects small liver grafts through HSP induction; and (c) whether the potential benefits of preconditioning on HSP is related to IL-1 inhibition. Our results, obtained with an IL-1 receptor antagonist, indicated the injurious effects of IL-1 in ischaemia-reperfusion (I/R) injury and established a relationship between IL-1 and growth factors. Thus, IL-1 reduced hepatocyte growth factor (HGF) and promoted TGFbeta release, thus contributing to the impaired liver regeneration associated with ROLT. Preconditioning inhibited IL-1 through nitric oxide (NO), thereby protecting against the injurious effects of IL-1. In addition, by another pathway independent of NO, preconditioning induced HSP70 and haem-oxygenase-1 (HO-1). HO-1 protected against I/R injury and liver regeneration, whereas the benefits resulting from HSP70 were mainly related to hepatocyte proliferation. These results suggest a mechanism that explains the effectiveness of preconditioning in ROLT. They suggest, too, that other strategies, in addition to preconditioning, that modulate IL-1 and/or HSPs could be considered in clinical situations requiring liver regeneration such as small liver grafts.

Activation pattern of mitogen-activated protein kinases in early phase of different size liver isografts in rats

Mitogen-activated protein kinases (MAPK) play a pivotal role in ischemia reperfusion injuries of heart and liver, but the activation pattern of MAPKs in the early phase of different size liver isografts remains unclear. The experiment is designed to investigate the activation pattern and role of MAPKs in isografts of the rat with different size liver transplantation. The animal models of different size graft liver transplantation (whole graft, 50% size, or 30% size, respectively) were established and the sham operation group served as a control. The recipients were sacrificed at 0.5-, 2-, 6-, and 24-hour time points after transplantation to harvest the graft specimens and blood samples. The serum aspartate amino transferase (AST), alanine amino transferase (ALT) and tumor necrosis factor-alpha (TNF-alpha) levels, and histological findings were evaluated. The expressions of the total and phosphorylated p46/p54 JNKs, p38 MAPK, and p42/p44 ERKs were detected by Western blot. The serum ALT and AST levels increased significantly at the 0.5-hour time point and maintained high with the peak levels at the 6-hour time point after liver transplantation. The different sizes of liver isografts did not change the expressions of total p46/p54JNKs, p38MAPK, and p42/p44 ERKs. While the expressions of phosphorylated p46/p54JNKs, p38 MAPK, and p42/p44 ERKs were either negative or mildly up-regulated in the sham operation group, they were significantly activated in the transplanted liver at the 0.5-hour time point, especially in the 30% size liver transplantation group. In conclusion, the activation of three MAPKs in liver isografts correlates with graft size and the JNK and p38 MAPK are responsible for the graft injury while the ERK signal pathway maybe participate in the regulation of cell growth and differentiation after small-for-size liver transplantation.

Small-for-size syndrome after partial liver transplantation: definition, mechanisms of disease and clinical implications

Widespread application of cadaveric split or living donor liver transplantation bears considerable potential to increase the pool of available organs and thus alleviate the problem of organ shortage. Although splitting of a cadaveric liver into two grafts for adult recipients can be performed successfully, sufficient function of undersized grafts is a major concern. To minimize the risk for living donors, transplant surgeons aim at procuring the least necessary liver volume, also leading to potentially small grafts. When small partial grafts are unable to meet the functional demands, the recipients can develop a so-called small-for-size syndrome (SFSS). There is currently limited data on the pathogenesis of SFSS, with clinical studies mainly focusing on portal hyperperfusion. Additional aspects include graft-related factors such as functional and regenerative capacity, as well as recipient-related factors, such as overall health status and severity of cirrhosis. However, there is currently no consensus on the definition of SFSS. We propose a novel definition, based on simple clinical criteria, which divides the syndrome into either nonfunction or dysfunction of a small graft after the exclusion of other causes. This definition should ease comparability of future clinical trials, and thus improve understanding of the pathogenesis of SFSS.